Detect world via Tags when switching meshing types.  update for changes in PluginAPI.

Signed-off-by: Nick Minkler <sleaker@gmail.com>
Merge pull request #6 from Grinch/master

Changes for ModEngine
Fixed a case where a npe would generate from clicking on non-world items
Add Hotbar

Signed-off-by: Steven Downer <grinch@outlook.com>